1. Field of the Invention
The present invention relates to a top end of a can having a stay-on-type tab, and more particularly, to a top end which is suitable for a beverage can.
2. Discussion of the Background
FIGS. 13 and 14 show a conventional can top end 2. This top end 2 consists of a disc-shaped panel 4 and a stay-on-type tab 10 fixed on the center of the panel 4, and the outer periphery of the panel 4 can be engaged to the upper end of a can body in a can-manufacturing process. Both panel 4 and tab 10 are commonly made of aluminum alloy.
The panel 4 has a C-shaped score 6 and a scored portion 8 surrounded by the score 6 in the upper surface thereof. The score 6 was formed by shallowly scoring the upper surface of the panel 4, and the score 6 starts from an adjacent point of the center portion of the panel 4, passes an adjacent point of the outer periphery of the panel 4, and terminates at the adjacent point of the center portion of the panel 4. In general, the score 6 consists of two parallel scores 61 and 62. The outer score 61 is the main score to be torn by pulling up the tab 10, and the inner score 62 is an auxiliary score which facilitates the tearing of the outer score 61.
The tab 10 has a pull-up end 10b and a push-down end 10a at both ends thereof. The push-down end 10a is located on the scored portion 8. Thus, the outer score 61 can be torn by pulling up the pull-end 10b of the tab 10, and thus, the scored portion 8 is opened. The tab 10 is fixed to the panel 4 as shown in FIG. 14. That is, in the center of the panel 4, a protrusion 12 is formed, and the protrusion 12 is riveted through a connecting hole of the tab 10.
According to the above-mentioned top end 2, it Is possible to open the scored portion 8 without detaching the tab 10 from the top end 2. However, it has been pointed out that the top end 2 of this type makes it difficult to drink the contents of a can, in comparison with a top end having a detachable tab.
The reasons of this difficulty are as follows.
1) In the above-described top end 2, after the scored portion 8 is opened by pulling up the tab 10, the push-down end 10a of the tab 10 protrudes inside the opening. Therefore, when a person drinks the contents of the can, the tab 10 comes into contact with the person's nose or upper lip and prevents fitting of the lips around the periphery of the opening.
2) In the top end 2, as the area of the scored portion 8 becomes larger, the force which is necessary to tear open the scored portion 8 increases. Therefore, in order to facilitate the opening operation, the scored portion 8 should be relatively small. Thus, inflow of air into the can is restricted by the small size of the opening of the can end 2, and outflow of the contents is hindered.
Additionally, in the recent years, it has been desirable to reduce the diameter of the top end 2 in order to reduce manufacturing costs. However, if the diameter of the top end 2 Is made smaller, the distance between the push-down end 10a of the tab 10 and the outer periphery of the top end 2 becomes small, and interference of the tab 10 with the nose or lip of a drinker is increased. Furthermore, if the size of the scored portion 8 is made smaller in order to reduce the diameter of the top end, it becomes more difficult to smoothly drink the contents of the can. Therefore, the conventional top end 2 is insufficient to meet the demands of reducing the manufacturing costs of cans.